class Solution(object):
    def findDifferentBinaryString(self, nums):
        nums = {int(num, 2) for num in nums}
        n = len(nums)
        val = 0
        while True:
            if val not in nums:
                val = str(bin(val))[2:]
                return '0' * (n - len(val)) + val
            else:
                val += 1
